Checks by gear type
Category-specific points to inspect on vintage or modified guitars, amplifiers, effects, synths and keyboards.
On digital or hybrid instruments, configuration is not limited to visible hardware. Firmware, ROMs, memory expansions, storage and internal modifications can change features and compatibility.
Before buying or selling, record the software version where verifiable, installed expansions and differences from standard configuration.
If an update is irreversible or requires specific hardware, treat it as a significant modification.
Keep legitimate backups and maintenance files where appropriate, without confusing installed content with the physical originality of the instrument.
Tuners, bridges, saddles, pickguards, knobs and strap buttons are often replaced because of wear or preference.
Check whether the replacement uses existing holes, whether impressions from earlier hardware remain and whether removed parts have been retained. A reversible upgrade with the original hardware included is different from a change requiring new drilling or machining.
Also consider correct function: a damaged original component may have documentary value without being the best choice for daily use.
Always describe what is fitted now and what is supplied separately.